1. Field of the Invention
The present invention relates to an elevator control apparatus utilizing a power storage unit.
2. Description of the Related Art
A conventional elevator control apparatus will be described with reference to an accompanying drawing. FIG. 8 shows a construction of a conventional elevator control apparatus disclosed, for example, under a title of xe2x80x9cRedesigned medium-to-low speed passenger elevator, Grandyxe2x80x9d on page 9 of Mitsubishi Denki Giho (written by Ando, Kimura, and Mori, Vol. 70, No. 11 issued in 1996).
The conventional elevator control apparatus shown in FIG. 8 includes a commercial three-phase AC power source 1, a motor 2, such as an induction motor IM, a hoisting machine 3, a rope 4, an elevator car 5, a counterweight 6, an encoder 7, a controller 8, a converter 9 formed of a diode or the like, a capacitor 10, a current detector 11, such as a current transformer (CT), an inverter 12, an inverter control circuit 13, a gate drive circuit 14, a regenerative resistor 15, and a switching means 16, such as an IGBT.
An operation of the aforesaid conventional elevator control apparatus will now be described with reference to the drawing.
The hoisting machine 3 is driven by the motor 2 to move the elevator car 5 and the counterweight 6 connected to both ends of the rope 4, thereby carrying passengers in the car to a predetermined floor.
The converter 9 rectifies AC power supplied from the commercial power source 1 to convert it into DC power, which is stored in the capacitor 10. The DC power is converted into AC power of a variable voltage and a variable frequency by the inverter 12.
The controller 8 controls starts and stops of the elevator and also creates commands for start and stop positions and speed. Based on a speed command supplied by the controlled 8, the inverter control circuit 13 rotationally drives the motor 2 by reflecting current feedback from the current detector 11 and speed feedback from the encoder 7 mounted on the hoisting machine 3, thereby implementing the position and speed control of the elevator. At this time, the inverter control circuit 13 controls output voltages and frequencies of the inverter 12 via the gate drive circuit 14.
The counterweight 6 of the elevator is set such that it is balanced when the car 5 is loaded with a moderate number of passengers. For example, when the elevator travels in a balanced state, it is possible to increase the speed of the elevator while consuming electric power in an acceleration mode, and to turn accumulated speed energy back into electric power in a deceleration mode. In typical elevators, however, the regenerative electric power is consumed by being converted into heat energy by the regenerative resistor 15 by controlling the switching means 16.
The conventional elevator control apparatus described above operates the elevator by constantly supplying electric power from the commercial power source. This has been posing a problem in that the operation of the elevator cannot be performed in case of a power failure of the commercial power source, and power consumption cannot be reduced even during a peak time zone of consumption of electric power.
There has been another problem in that the electric power produced during a regenerative mode of the elevator is thermally consumed by a regenerative resistor and cannot be effectively used.
The present invention has been made with a view toward solving the problems mentioned above, and it is an object of the present invention to provide an elevator control apparatus capable of landing in case of a power failure, eliminating a peak when power is used, and achieving energy saving by effectively utilizing electric power generated in a regenerative mode of an elevator.
To this end, according to one aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a charge/discharge control circuit that controls a state of charge of the power storage unit, outputs a drive signal to charge the power storage unit with the DC power during a halt of the elevator based on operational information regarding the elevator received from the controller, and outputs a stop signal to stop charging when a voltage of the power storage unit reaches a preset predetermined voltage; and a charge/discharge circuit for starting charging the power storage unit with the DC power in response to the drive signal, and stopping the charging in response to the stop signal.
In a preferred form of the present invention, the elevator control apparatus further includes temperature detecting means for detecting a temperature of the power storage unit, and the charge/discharge control circuit changes the predetermined voltage based on the temperature of the power storage unit detected by the temperature detecting means.
In another preferred form of the elevator control apparatus according to the present invention, the charge/discharge control circuit corrects the state of charge of the power storage unit when a voltage of the power storage unit reaches the predetermined voltage.
According to another aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an, elevator; a power storage unit for storing the DC power; a charge/discharge circuit for charging the power storage unit or causing the power storage unit to discharge according to a drive signal; and a charge/discharge control circuit that controls a state of charge of the power storage unit, outputs a drive signal for charging the power storage unit or causing the power storage unit to discharge, and corrects the state of charge based on an open circuit voltage of the power storage unit when a preset predetermined time elapses from completion of discharging from the power storage unit for operating the elevator.
According to yet another aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a charge/discharge circuit for charging the power storage unit or causing the power storage unit to discharge according to a drive signal; and a charge/discharge control circuit that controls a state of charge of the power storage unit, outputs a drive signal for charging the power storage unit or causing the power storage unit to discharge, and corrects the state of charge based on an open circuit voltage of the power storage unit when a preset predetermined time elapses from completion of charging the power storage unit.
In a preferred form of the present invention, the elevator control apparatus further includes temperature detecting means for detecting a temperature of the power storage unit, and the charge/discharge control circuit corrects the state of charge based on the temperature of the power storage unit detected by the temperature detecting means and the open circuit voltage.
According to a further aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a charge/discharge circuit for charging the power storage unit or causing the power storage unit to discharge according to a drive signal; charge target indicating means for indicating a target value for charging the power storage unit; and a charge/discharge control circuit that controls a state of charge of the power storage unit, outputs a drive signal for charging the power storage unit or causing the power storage unit to discharge, and controls the charge/discharge circuit so as to cause the power storage unit to discharge for a purpose other than operating the elevator if the state of charge indicates that a charge level is higher than the charge target value.
According to another aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a charge/discharge circuit for charging the power storage unit or causing the power storage unit to discharge according to a drive signal; a charge/discharge control circuit that outputs a drive signal for charging the power storage unit or causing the power storage unit to discharge, and transmits the state of charge of the power storage unit; and a remote monitoring unit that is installed at a remote location and controls the state of charge of the power storage unit that has been transmitted.
In a preferred form of the elevator control apparatus according to the present invention, the remote monitoring unit calculates charge current amount efficiency at the time of remote monitoring by measuring a charge amount until a preset voltage corresponding to a discharge amount of the power storage unit is reached, and estimates a life of the power storage unit based on the calculated charge current amount efficiency.
According to a further aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a charge/discharge circuit for charging the power storage unit or causing the power storage unit to discharge according to a drive signal; displaying means for externally indicating the state of charge of the power storage unit; and a charge/discharge control circuit that outputs a drive signal for charging the power storage unit or causing the power storage unit to discharge, controls a state of charge of the power storage unit, and drives the displaying means to cause the displaying means to indicate the state of charge of the power storage unit.
In a preferred form of the elevator control apparatus according to the present invention, the charge/discharge control circuit corrects the state of charge of the power storage unit when the voltage of the power storage unit reaches the predetermined voltage.